1 /* 2 * Test cases for <linux/hash.h> and <linux/stringhash.h> 3 * This just verifies that various ways of computing a hash 4 * produce the same thing and, for cases where a k-bit hash 5 * value is requested, is of the requested size. 6 * 7 * We fill a buffer with a 255-byte null-terminated string, 8 * and use both full_name_hash() and hashlen_string() to hash the 9 * substrings from i to j, where 0 <= i < j < 256. 10 * 11 * The returned values are used to check that __hash_32() and 12 * __hash_32_generic() compute the same thing. Likewise hash_32() 13 * and hash_64(). 14 */ 15 16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n" 17 18 #include <linux/compiler.h> 19 #include <linux/types.h> 20 #include <linux/module.h> 21 #include <linux/hash.h> 22 #include <linux/stringhash.h> 23 #include <linux/printk.h> 24 25 /* 32-bit XORSHIFT generator. Seed must not be zero. */ 26 static u32 __init __attribute_const__ 27 xorshift(u32 seed) 28 { 29 seed ^= seed << 13; 30 seed ^= seed >> 17; 31 seed ^= seed << 5; 32 return seed; 33 } 34 35 /* Given a non-zero x, returns a non-zero byte. */ 36 static u8 __init __attribute_const__ 37 mod255(u32 x) 38 { 39 x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */ 40 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */ 41 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */ 42 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */ 43 return x; 44 } 45 46 /* Fill the buffer with non-zero bytes. */ 47 static void __init 48 fill_buf(char *buf, size_t len, u32 seed) 49 { 50 size_t i; 51 52 for (i = 0; i < len; i++) { 53 seed = xorshift(seed); 54 buf[i] = mod255(seed); 55 } 56 } 57 58 /* 59 * Test the various integer hash functions. h64 (or its low-order bits) 60 * is the integer to hash. hash_or accumulates the OR of the hash values, 61 * which are later checked to see that they cover all the requested bits. 62 * 63 * Because these functions (as opposed to the string hashes) are all 64 * inline, the code being tested is actually in the module, and you can 65 * recompile and re-test the module without rebooting. 66 */ 67 static bool __init 68 test_int_hash(unsigned long long h64, u32 hash_or[2][33]) 69 { 70 int k; 71 u32 h0 = (u32)h64, h1, h2; 72 73 /* Test __hash32 */ 74 hash_or[0][0] |= h1 = __hash_32(h0); 75 #ifdef HAVE_ARCH__HASH_32 76 hash_or[1][0] |= h2 = __hash_32_generic(h0); 77 #if HAVE_ARCH__HASH_32 == 1 78 if (h1 != h2) { 79 pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x", 80 h0, h1, h2); 81 return false; 82 } 83 #endif 84 #endif 85 86 /* Test k = 1..32 bits */ 87 for (k = 1; k <= 32; k++) { 88 u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */ 89 90 /* Test hash_32 */ 91 hash_or[0][k] |= h1 = hash_32(h0, k); 92 if (h1 > m) { 93 pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m); 94 return false; 95 } 96 #ifdef HAVE_ARCH_HASH_32 97 h2 = hash_32_generic(h0, k); 98 #if HAVE_ARCH_HASH_32 == 1 99 if (h1 != h2) { 100 pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() " 101 " = %#x", h0, k, h1, h2); 102 return false; 103 } 104 #else 105 if (h2 > m) { 106 pr_err("hash_32_generic(%#x, %d) = %#x > %#x", 107 h0, k, h1, m); 108 return false; 109 } 110 #endif 111 #endif 112 /* Test hash_64 */ 113 hash_or[1][k] |= h1 = hash_64(h64, k); 114 if (h1 > m) { 115 pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m); 116 return false; 117 } 118 #ifdef HAVE_ARCH_HASH_64 119 h2 = hash_64_generic(h64, k); 120 #if HAVE_ARCH_HASH_64 == 1 121 if (h1 != h2) { 122 pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() " 123 "= %#x", h64, k, h1, h2); 124 return false; 125 } 126 #else 127 if (h2 > m) { 128 pr_err("hash_64_generic(%#llx, %d) = %#x > %#x", 129 h64, k, h1, m); 130 return false; 131 } 132 #endif 133 #endif 134 } 135 136 (void)h2; /* Suppress unused variable warning */ 137 return true; 138 } 139 140 #define SIZE 256 /* Run time is cubic in SIZE */ 141 142 static int __init 143 test_hash_init(void) 144 { 145 char buf[SIZE+1]; 146 u32 string_or = 0, hash_or[2][33] = { 0 }; 147 unsigned tests = 0; 148 unsigned long long h64 = 0; 149 int i, j; 150 151 fill_buf(buf, SIZE, 1); 152 153 /* Test every possible non-empty substring in the buffer. */ 154 for (j = SIZE; j > 0; --j) { 155 buf[j] = '\0'; 156 157 for (i = 0; i <= j; i++) { 158 u64 hashlen = hashlen_string(buf+i); 159 u32 h0 = full_name_hash(buf+i, j-i); 160 161 /* Check that hashlen_string gets the length right */ 162 if (hashlen_len(hashlen) != j-i) { 163 pr_err("hashlen_string(%d..%d) returned length" 164 " %u, expected %d", 165 i, j, hashlen_len(hashlen), j-i); 166 return -EINVAL; 167 } 168 /* Check that the hashes match */ 169 if (hashlen_hash(hashlen) != h0) { 170 pr_err("hashlen_string(%d..%d) = %08x != " 171 "full_name_hash() = %08x", 172 i, j, hashlen_hash(hashlen), h0); 173 return -EINVAL; 174 } 175 176 string_or |= h0; 177 h64 = h64 << 32 | h0; /* For use with hash_64 */ 178 if (!test_int_hash(h64, hash_or)) 179 return -EINVAL; 180 tests++; 181 } /* i */ 182 } /* j */ 183 184 /* The OR of all the hash values should cover all the bits */ 185 if (~string_or) { 186 pr_err("OR of all string hash results = %#x != %#x", 187 string_or, -1u); 188 return -EINVAL; 189 } 190 if (~hash_or[0][0]) { 191 pr_err("OR of all __hash_32 results = %#x != %#x", 192 hash_or[0][0], -1u); 193 return -EINVAL; 194 } 195 #ifdef HAVE_ARCH__HASH_32 196 #if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */ 197 if (~hash_or[1][0]) { 198 pr_err("OR of all __hash_32_generic results = %#x != %#x", 199 hash_or[1][0], -1u); 200 return -EINVAL; 201 } 202 #endif 203 #endif 204 205 /* Likewise for all the i-bit hash values */ 206 for (i = 1; i <= 32; i++) { 207 u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */ 208 209 if (hash_or[0][i] != m) { 210 pr_err("OR of all hash_32(%d) results = %#x " 211 "(%#x expected)", i, hash_or[0][i], m); 212 return -EINVAL; 213 } 214 if (hash_or[1][i] != m) { 215 pr_err("OR of all hash_64(%d) results = %#x " 216 "(%#x expected)", i, hash_or[1][i], m); 217 return -EINVAL; 218 } 219 } 220 221 /* Issue notices about skipped tests. */ 222 #ifndef HAVE_ARCH__HASH_32 223 pr_info("__hash_32() has no arch implementation to test."); 224 #elif HAVE_ARCH__HASH_32 != 1 225 pr_info("__hash_32() is arch-specific; not compared to generic."); 226 #endif 227 #ifndef HAVE_ARCH_HASH_32 228 pr_info("hash_32() has no arch implementation to test."); 229 #elif HAVE_ARCH_HASH_32 != 1 230 pr_info("hash_32() is arch-specific; not compared to generic."); 231 #endif 232 #ifndef HAVE_ARCH_HASH_64 233 pr_info("hash_64() has no arch implementation to test."); 234 #elif HAVE_ARCH_HASH_64 != 1 235 pr_info("hash_64() is arch-specific; not compared to generic."); 236 #endif 237 238 pr_notice("%u tests passed.", tests); 239 240 return 0; 241 } 242 243 static void __exit test_hash_exit(void) 244 { 245 } 246 247 module_init(test_hash_init); /* Does everything */ 248 module_exit(test_hash_exit); /* Does nothing */ 249 250 MODULE_LICENSE("GPL"); 251